USB PD Charger Components: 929 Disc Capacitors, Five Empty Columns, Zero Datasheets

The Y capacitor is the one USB PD charger component we cannot fully specify. We hold no disc capacitor datasheet at all, 5 of the 11 columns in Walsin’s 929-row disc export are empty on every row, and none of the 929 appears in our 23 September 2026 stock snapshot.

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Venatech Limited, an authorised Walsin distributor in Hong Kong, holds the full parametric export published by Walsin Technology (Walsin) and 28 Walsin datasheets covering 451 pages. This post is measured from Walsin_DiscCap_ALL.xlsx (929 rows), 00_ALL_MLCC_parts_combined.xlsx (24,026 rows) and the 137 chip resistor exports (234,815 rows), and checked against the approval sheets we actually hold. Every part number is real, and every absence is stated rather than glossed.

Which Walsin lines does a USB-C PD charger actually draw on?

Five, and we hold a datasheet for two of them. A 65 W USB-C Power Delivery charger needs a Y capacitor across the isolation barrier, a high-voltage ceramic for the primary snubber, a safety-rated bleeder and start-up resistor chain, bulk output ceramics and a surge-tolerant sense network. We counted what Walsin publishes on each, then checked it against our own datasheet library.

Charger function	Walsin line	Part numbers in the export	Datasheet we hold	Match / mismatch between export and documentation
Y capacitor, leaded	Disc safety certificated, AH / AC / AS	367 of 929 disc rows	None	Mismatch — no approval sheet, no lead pitch, no temperature coefficient
Y capacitor, surface mount	Safety certificated MLCC, S2	173	16_Safety_X1Y2_General_S2.pdf, 14 pages	Match on series; mismatch — the export’s Rated Voltage column is the impulse voltage, not the working voltage
Primary snubber ceramic	Middle and High Voltage MLCC, 200 V to 4 kV	4,095	04_Middle_and_High_Voltage.pdf	Match — series documented and the voltage grid is published
Bleeder and start-up resistor	Thick Film High Voltage, including a UL Safety Certification sub-series	20,244, of which 3,004 carry the UL safety designation	None	Mismatch — the series name claims a certification we hold no file number for
Surge-tolerant sense network	Thick Film Anti-Surge and Triple Power Surge	17,180	None	Mismatch — the two resistor sheets we hold cover general purpose only

Three of the five lines a charger needs are undocumented on our shelf. We have not seen a distributor publish that table about its own range, and publishing it is the point.

Why does the X1 rating decide the Y class for you?

Because Walsin’s safety disc range offers only one Y class at three of its four AC ratings. We re-measured all 367 safety certificated disc rows for this post. 400 Vac is Y1 and nothing else. 440 Vac is Y2 and nothing else. Only 500 Vac offers both. 760 Vac is Y1 only. This is our own count, first published earlier in this corpus, and it holds exactly on re-measurement.

X1 rating	Y1 part numbers	Y2 part numbers	Series present
X1-400 Vac	112	0	AH
X1-440 Vac	0	137	AC, including the automotive variant
X1-500 Vac	54	49	AH 500 V and AC 500 V
X1-760 Vac	15	0	AS

The design consequence is blunt. If your creepage and clearance work has already fixed the Y class, you have also fixed the AC rating, and with it the series, the dielectric choices and the physical size family. The class is not a column you tick independently. It is downstream of a number you chose two weeks earlier.

What does the disc capacitor export leave out?

Half the fields you need to lay out a leaded part. We opened Walsin_DiscCap_ALL.xlsx and checked every column for content. It has 11 columns, and 5 of them are empty on all 929 rows: T.C., Lead Spacing, Packing, SPQ and MOQ. What survives is the part number, the series, the dielectric, the capacitance, the tolerance and the AC or DC rating.

That means the export publishes no lead pitch for a through-hole safety capacitor and no temperature coefficient for a Class I disc. We hold no disc capacitor datasheet to fill either gap — none of our 28 Walsin PDFs covers the line. So for YP0AC102K080 we can tell you it is 1000 pF, ±10%, X1-440 Vac / Y2-250 Vac, in the AC series, and we cannot tell you the lead spacing, the body diameter, the insulation resistance, the dissipation factor or the climatic category from any document we hold.

The capacitance code in the part number is a partial substitute, and worth trusting over the column. We decoded all 367 safety rows: YU0AS103M190 is the only one whose code and Capacitance column disagree. Its code reads 103, or 10,000 pF, while the column reads 1000 pF — and the real 1000 pF part at that rating is YU0AS102M080. The trailing digits move from 080 to 190, consistent with the larger part.

Is there a surface-mount Y capacitor we can actually document?

Yes, and it is the one part of the charger where the documentation is strong. The S2 safety certificated MLCC series holds 173 part numbers, and we hold its 14-page approval sheet, 16_Safety_X1Y2_General_S2.pdf, dated April 2026. We read it. It states the working voltage as X1 310 Vac and Y2 250 Vac, with 1500 Vdc on all models, and a separate 250 Vac figure for the CQC scheme. Peak impulse voltage is 5000 V to 6000 V. Test standards are EN 60384-14 : 2023, IEC 60384-14 : 2023 and UL 60384-14 : 2025 (Ed 3.0).

This matters because the export disagrees with itself here, and the datasheet is what resolves it. All 173 S2 rows show 5000Vdc or 6000Vdc in the Rated Voltage column. That is the impulse voltage — the sheet’s ordering key says so explicitly, decoding 502 as 5000 V impulse voltage — and the AC working voltage appears nowhere in the export. A selector that reads the column literally will tell you Walsin sells a 5 kV Y capacitor. It does not.

The S2 envelope is narrow: 1808 to 2220 sizes, NP0 from 3 pF to 2200 pF and X7R from 100 pF to 10 nF. S242B102K502 is an 1808 X7R 1000 pF part and S252B222K502 is a 2211 X7R 2200 pF part. Both were in the Hong Kong snapshot on 23 September 2026. And the credential behind the series is checkable without asking us: UL file E182369 is searchable in UL’s own public database in about thirty seconds.

How do the 35 candidates at the 1000 pF Y position differ?

By class, by AC rating, by dielectric and by physical size — never by capacitance. We counted every safety disc row at exactly 1000 pF: 35 part numbers, 18 of them Y1 and 17 Y2, spread across three dielectrics. Here is the same 1000 pF requirement answered six ways. We will not tell you a part is interchangeable. We will show you where it differs.

Part number	Series	Dielectric	Tolerance	Rating	Match / mismatch vs X1/Y2 at 250 Vac mains, 1000 pF
YP0AC102K080	AC, X1/Y2	YP (Y5P)	±10%	X1-440 Vac / Y2-250 Vac	Match on class, rating, value; tightest tolerance of the Y2 group
YU0AC102M060	AC, X1/Y2	YU (Y5U)	±20%	X1-440 Vac / Y2-250 Vac	Match on class and rating; mismatch — Y5U dielectric, ±20%
YP1AC102K080	AC, X1/Y2	YP (Y5P)	±10%	X1-440 Vac / Y2-300 Vac	Match on class and value; mismatch — 300 Vac Y rating, different part
YP0AH102K100	AH, X1/Y1	YP (Y5P)	±10%	X1-400 Vac / Y1-250 Vac	Match on value and Y voltage; mismatch — Y1 class, 400 Vac X1
YP5AC102K080	AC 500 V, X1/Y2	YP (Y5P)	±10%	X1-500 Vac / Y2-500 Vac, 1500 Vdc	Match on class and value; mismatch — 500 Vac Y rating, larger family
S242B102K502	S2 safety MLCC	X7R	±10%	X1 310 Vac / Y2 250 Vac, 1500 Vdc	Match on class, Y voltage and value; mismatch — surface mount 1808, lower X1 rating, documented

Six candidates, one capacitance, and the only one we can hand you an approval sheet for is the surface-mount part. That is the trade: the leaded Y capacitor is the conventional answer and the undocumented one; the S2 ceramic is the documented answer and the one that constrains your layout to an 1808 or larger pad.

Which charger resistors claim a safety certification we cannot source?

The high-voltage series, on 3,004 part numbers. We counted 20,244 rows across Walsin’s Thick Film High Voltage chip resistor families, and 3,004 of them sit in a sub-series the export names Thick Film High Voltage Chip Resistor UL Safety Certification — 1,502 commercial and 1,502 automotive, across 0603, 0805, 1206, 2010 and 2512 at 1/10 W to 1 W. WF12N1004FTL is one of them: 1206, 1 MΩ, ±1%, TCR ≦±100 ppm/°C, 1/4 W.

We then checked our resistor documentation. We hold exactly two chip resistor datasheets, Walsin_MR_Automotive_Thick_Film_Chip_Resistor.pdf and Walsin_WR_General_Purpose_Chip_Resistor.pdf, 20 pages between them. The string “UL” appears zero times in either. Neither sheet mentions a high-voltage series at all. Our only named UL file, E182369, covers Walsin’s safety capacitor line, not its resistors.

Which of these parts was in Hong Kong on 23 September 2026?

Almost none of the safety content, and a useful amount of everything else. We checked all five lines against the ready-stock snapshot as at 23 September 2026, which lists 1,125 catalogue codes.

Line	Part numbers in the export	In the 23 September 2026 snapshot
Disc capacitors, all series	929	0
S2 safety certificated MLCC	173	2
Middle and High Voltage MLCC	4,095	149
Anti-surge and Triple Power Surge resistors	17,180	4

Zero of 929. Not one disc capacitor of any kind, safety or general, was in that snapshot. That is the single most useful sentence in this post for a charger design, because it says the Y capacitor is a lead-time item rather than a shelf item, and it says which way the surface-mount alternative is worth evaluating. The trade press reported MLCC lead times in the 26 to 32 week range through 2026 as AI server and electric vehicle build-outs pulled on the same capacity.

For the snubber, 149 middle-and-high-voltage part numbers were on the shelf, and 1206B102K631 at 630 Vdc and 1206B102J102 at 1000 Vdc are both real 1206 X7R 1000 pF positions in that series. Stock is always a dated snapshot, never a live feed.

The short version

A USB-C PD charger draws on five Walsin lines and we hold a datasheet for two. The Y capacitor is the weak link: 367 safety certificated disc part numbers, 929 disc rows in total, no approval sheet on our shelf, and 5 of the 11 export columns empty on every row — temperature coefficient, lead spacing, packing, pack quantity and minimum order quantity. The Y class is not yours to choose: 400 Vac is Y1 only across 112 parts, 440 Vac is Y2 only across 137, 500 Vac offers both, 760 Vac is Y1 only. The documented alternative is the S2 surface-mount series, 173 parts, whose 14-page approval sheet gives X1 310 Vac, Y2 250 Vac and 1500 Vdc while the export column shows a 5000 V impulse figure instead. 3,004 high-voltage resistors carry a UL safety designation we hold no file number for. Zero of 929 disc capacitors were in Hong Kong on 23 September 2026. Qualification stays with you.

Send us the isolation-barrier and primary-side lines off your charger BOM and we will come back with Walsin candidates field by field — including which specifications we can hand you an approval sheet for today and which ones we would have to ask Walsin for on your behalf. We will tell you what we do not have. Nobody else will. And if your current Y capacitor was selected from a parametric table with the lead spacing column blank, tell us: we would like to know how many designs that has happened to.

For the class decision in detail, see X1/Y1 vs X1/Y2 safety capacitors. For the disc series themselves, see disc capacitor safety classes AH, AC and AS. For the column that reads 5000 Vdc and should not, see safety capacitor rated voltage: 173 rows read 5000Vdc. Cross the whole charger BOM in one pass with the free cross-reference tool — paste up to 500 part numbers or drop your Excel or CSV, matched against Walsin’s published catalogue, with every difference from your original stated rather than hidden, and a safety-certified filter among the special requirements. Then check ready stock, a dated snapshot as at 23 September 2026. The leaded range sits on the Walsin disc capacitor page. Reach us at Unit 207, 2/F, Sun Ling Plaza, 30 On Kui Street, Fanling, N.T., Hong Kong, or on (852) 2628 4777.

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